Fittings are commonly defined upon conduit ends permitting interconnection of conduits, or attachment thereof to other fittings, adapters, hose, etc. Most conduit fittings utilize threads for attachment, or the assembly of hose fittings to metal conduits, and accordingly, rotational torque forces are often applied to the conduit and its associated fittings or components. Such torque forces are commonly resisted by the use of a wrench engaging wrench flats fixed relative to the conduit.
In the past, wrench flats on conduits have been defined upon nipples or adapters soldered, brazed, swaged, or otherwise mechanically attached to the conduit, and it is also known to shape the conduit material, itself, into a noncircular configuration throughout a limited axial length to form parallel flat surfaces suitable for wrench engagement. It is also known to braze, solder or weld wrenching nuts or rings to cylindrical elements such as a conduit to permit torque transfer members to be applied thereto.
Prior art devices of the aforedescribed types, especially those requiring heat, are expensive to fabricate, requiring rather complex secondary operations including heating and cooling stages.
It is an object of the invention to attach wrenching means to a metal conduit by a simple mechanical process not requiring external heat.
Another object of the invention is to provide a method for attaching a wrenching nut to a deformable metal conduit wherein the conduit metal is radially deformed into a mechanical relationship with a wrenching nut.
Yet another object of the invention is to provide a method of affixing a wrenching nut to a deformable metal conduit wherein only the material of the conduit is utilized to produce a mechanical interconnection with the nut, and the process may be quickly and economically achieved.
Another object of the invention is to produce an assembly between a metal conduit and a wrenching nut wherein the conduit material is outwardly radially deformed into engagement with keying recesses defined in lateral sides of the nut which include radially disposed surfaces effectively capable of establishing a torque transmitting relationship between the nut and conduit.
In the practice of the invention a deformable metal conduit, such as of soft steel, copper, brass, aluminum, or the like, receives an annular wrenching nut slipped thereover. The nut includes an outer periphery having wrench-engageable flats defined thereon, usually of a hexagon configuration, and the lateral sides of the nut include recesses having surfaces of a generally radial orientation.
Upon the nut being axially positioned on the conduit as desired, the conduit is radially deformed in the region of the nut in an outward direction by the application of axial forces thereto. This outward deformation of the conduit throughout its circumference forces the conduit material into engagement with the nut on each lateral side axially positioning the nut. Further, the deformed conduit material enters the nut recesses and engages the radial surfaces thereof which prevents relative rotation between the nut and conduit permitting the transmission of torque forces therebetween.
The desired directional flow of the conduit material during deformation is achieved by dies surrounding the conduit worked portion, and if desired, axial forces may be applied to the deformed conduit material to assure initimate contact of the conduit material with the nut lateral sides.
The practice of the invention permits an effective mechanical interconnection between a wrenching nut and a conduit without the application of external heat or bonding materials.